# Resonant frequencies in air filled closed cylinder

I want to calculate the resonant frequencies of a closed cylinder covered with rigid walls. The cylinder is of dimensions: diameter = $$1m$$, length = $$1m$$. Would this fundamental mode formula be correct to use in this case:

$$f = \frac{v_{sound}}{2L}$$

I think it is only valid for one-dimensional ducts such that diameter $$\ll$$ length but I am not sure about this. Could you please help me out with an explanation and how the above formula was derived and in which conditions is it valid to be used?

• This formula is for a cylinder open at one end. Is this your type of cylinder? – nasu Mar 21 '19 at 19:51
• Yes that's right. Thank you. I have just corrected the formula. – Becay Mar 22 '19 at 4:52